Jake Kenneally 9e04eec072 feat: Add percentage support to CSS properties (#738) ...

## Summary
- Closes #730

**What is the goal of this PR?**
- Adds percentage-based value support to CSS properties that accept
percentages (padding, margin, text-indent)
 
**What changes are included?**
- Adds `Percent` as another CSS unit
- Passes the viewport width to `fromCssStyle` so that we can resolve
percentage-based values
- Adds a fallback of using an emspace for text-indent if we have an
unresolvable value for whatever reason

## Additional Context

- This was missed in my CSS support feature, and the fallback when we
encounter a percentage value is to use px instead. This means 5% (which
would be ~30px on the screen) turns into 5px. When percentages are used
in `text-indent`, this fallback behavior makes the indent look like a
single space character. Whoops! 😬

My test EPUB has been updated
[here](https://github.com/jdk2pq/css-test-epub) with percentage based
CSS values at the end of the book.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**YES**_, Claude Code

2026-02-09 08:32:45 +11:00

..

Epub

feat: Add percentage support to CSS properties (#738)

2026-02-09 08:32:45 +11:00

Epub.cpp

feat: UI themes, Lyra (#528)

2026-02-05 21:50:11 +11:00

Epub.h

feat: UI themes, Lyra (#528)

2026-02-05 21:50:11 +11:00